Effects of inorganic and triethyl lead and inorganic mercury on the voltage activated calcium channel of Aplysia neurons.

Using conventional two electrode voltage clamp techniques we have studied the effects of Pb2+, triethyl lead (TEL) and Hg2+ on voltage-activated calcium channels of Aplysia neurons and found that all three metals are potent inhibitors at micromolar concentrations. However, the time course of current reduction or block and its reversibility vary when comparing Pb2+ to TEL and Hg2+. With application of Pb2+ the calcium current decreases immediately and a steady state is reached within three to seven minutes, depending upon the concentration of Pb2+ (IC50 = 61 microM). The block was easily reversed upon wash out of Pb2+ with a time course similar to that of onset. Perfusion with either TEL (5 to 50 microM) or Hg2+ (5 to 200 microM) resulted only in a small reduction of current when the substances reached the cell membrane but with clear reduction within 2 min. The decrease continued at about the same speed for the total duration of the application. Upon washing there was no recovery of the response. At the onset of washing the rate of current decline stopped for several minutes, but then the current continued to decline at a slower rate in the absence of toxicant. Our data suggest that Pb2+ acts by a direct and reversible blockade of the calcium channel. In contrast TEL and Hg2+ act slowly and irreversibly to block calcium channels at concentrations which do not greatly affect membrane potential or resistance. In spite of the slow time course these substances are probably acting directly on the calcium channel.     

Application of Microencapsulation Technology to Improve the Stability of Citral in Rodent Diets

Application of Microencapsulation Technology to Improve theStability of Citral in Rodent Diets. KUHN., G. O., MCCAMPBELL,P., SLNGMASTER, G., ARNESON, D. W., AND JAMESON, C. W. (1991).Fundam. Appl. Toxicol. 17, 635–640. Citral is a widelyused flavoring and scenting agent which is employed in numerousfood, industrial, and household products. Although the currentregulatory status of citral lists it as a GRAS chemical on theFDA list, the chemical is a reactive beta-substituted vinylaldehyde that has been shown to induce irritations of skin andmucous membranes, and to exhibit a dose-dependent teratogeniceffect on embryos of white leghorn chickens. Because of thesefactors, citral was nominated by the National Toxicology Programfor carcinogenesis study. Stability studies of dose formulationsof citral (0.02%) in NIH-07 rodent diet indicated a loss of41% of the citral after 1 day in a rat cage, due mainly to volatilityand reactivity with diet components. The chemical was subsequentlymicroencapsulated using a shell medium of food-grade modifiedcornstarch and sucrose, and then formulated into NIH-07 diet(0.02%) for various stability studies. Results after 7 daysin a rat cage showed 95% retention of chemical; diet that hadbeen stored 21 days retained 95% at 5°C storage and 89%at room temperature. An assessment of the purity of the citralin the microcapsules indicated that total impurities increasedfrom 0.7% in the neat chemical to 1.1% in the encapsulated chemical.     

The relationship of low-back pain, work history, work environment, and stress. A retrospective cross-sectional study of 38- to 64-year-old women

The association between low-back pain (LBP) and different work factors was investigated in a retrospective cross-sectional study of a random sample of 1,760 38- to 64-year-old women. The life-time incidence of LBP was 66% and the prevalence was 35%. In a univariate analysis, eight work variables correlated to LBP viz. more forward bending, more lifting, more standing, more monotonous work, dissatisfaction with the work tasks, dissatisfaction with the work environment, a higher degree of worry, and fatigue at the end of the work day. In a covariate analysis, however, only the three psychological variables remained directly associated to LBP viz. dissatisfaction with the work environment, a higher degree of worry, and fatigue at the end of the work day.     

Myopia and plasma cortisol

Estimation of plasma cortisol by fluorometric technique desorbed by Mallingly's was carried out in 56 cases, including 38 cases of myopia (19 cases of simple myopia and 19 cases of degenerative myopia) and 18 normal individuals. Urinary 17-keto steroids/24 hours was also estimated by Zimmermann technique in 12 out of the 56 cases, which include 8 cases of myopia (4 cases of simple myopia and 4 cases of degenerative myopia) and 4 normal individuals as control. Plasma cortisol level is lower in simple and degenerative myopia than in normal subjects, but on statistical analysis the difference was not of much significance. Patients with simple myopia with positive family history showed lower value of plasma cortisol than patients with simple myopia with negative family history, the difference was also statistically insignificant (P-0.1). In degenerative myopia patients, with and without family history, there was very little difference in plasma cortisol level and statistically highly insignificant (P-0.8). Urinary 17 keto steroid/24 hour values are lower in simple and degenerative myopia than in normal subjects.     

Systemic Vasculitis with Renal Involvement — A Review

Twenty five patients with renal vasculitis presenting over an eight year period were reviewed. Ten had microscopic polyarteritis, 6 classic polyarteritis, 5 overlap syndrome, 2 Churg-Strauss syndrome and 2 Wegener’s granulomatosis. Clinical features included hypertension, pulmonary involvement, neurological involvement and arthralgia. Serum creatinine was over 500 umol/1 in 13 patients, 10 of whom required dialysis. Visceral angiography was positive in 80% of those studied, Focal and segmental necrotising glomerulonephritis was the commonest renal lesion. Treatment consisted of corticosteroids and cytotoxic agents in most cases. Plasmapheresis was used for rapidly progressive renal failure, severe pulmonary haemorrhage or cerebral vasculitis. Improvement or stabilisation of renal function was seen in 68% of patients treated. There were 4 early deaths and one late death. The diagnosis, histology, treatment and outcome of renal vasculitis is discussed. The importance of early diagnosis and treatment is emphasised in this potentially reversible cause of acute renal failure.     

Diazepam-induced amnesia: a neuropharmacological model of an "organic amnestic syndrome"

Diazepam has well-known amnestic properties. These effects, however, are selective for certain psychobiologically distinct memory functions. In this study, incremental doses of diazepam administered to 10 normal volunteers selectively impaired anterograde episodic memory and attention while totally sparing access to information in long-term memory (semantic or knowledge memory). This pattern of disruption mimics that seen in patients with organic amnesias and is in sharp contrast to the pattern seen in patients with dementia. These findings provide a framework for defining specific psychobiological determinants of cognitive failure.     

Urethral blood circulation during cardiopulmonary bypass

The haemodynamic changes induced by extracorporeal circulation (ECC) are thought to be important in the induction of urethral strictures in open heart surgery when indwelling latex catheters are used. In the present study, 6 piglets were cannulated and connected to extracorporeal perfusion apparatus. Pump flows correlated with human ECC values with non-haemic prime were used. The mucosal and submucosal blood circulation in the urethra reduced by 66% during ECC (P less than 0.05). The brain and hepatic arterial flows increased. A significant reduction was seen in renal blood circulation. The changes in the urethral blood circulation during ECC correlated with previous findings. The reduced wash out levels of chemicals leaching from the indwelling latex catheters as a result of reduced local blood circulation are the main trigger for the induction of urethral strictures during ECC and in other shock-like circulatory disturbances in the human body.     

Cerebral lymphoma and HIV encephalitis in a case of paediatric AIDS,with Pre-Existing multicystic eneephalomalacia

A case of intracerebral malignant B cell lymphoma associated with encephalitis typical of Human Immunodeficiency Virus (HIV) infection is described in a 4 year old child, with post-transfusion Acquired Immune Deficiency Syndrome (AIDS) and severe pre-existing cystic encephalomalacia. This report further documents B cell lymphoma as the commonest cause of an intracerebral mass, and an important cause of death in paediatric AIDS. That more than one pathological process may be responsible for neurological symptoms in paediatric AIDS is also emphasised.     

The microbial flora of in-use blood pressure cuffs

The capacity of blood pressure cuffs to act as vehicles of hospital infection has been recognised. We describe the microbial flora of in-use DINAMAP blood pressure cuffs used in the operating theatres and one recovery room in a teaching hospital. Our results show significant microbial contamination of in-use blood pressure cuffs.